NewFeature Local borehole thermal resistance

[j-c-cook]

Is the local borehole thermal resistance computed and stored anywhere inside of the pipe objects?

[MassimoCimmino]

It is not computed or stored, since there is currently no use for it in the pipes module.

It could easily be evaluated at the initialization of pipe objects after the calculation of the _Rd matrix.

[j-c-cook]

I might need it for design purposes, and it would also be nice to have it as a reference point. Are you okay with adding a function that computes the local borehole resistance given a pipe object, mass flow rate and fluid?

[MassimoCimmino]

I see an opportunity for a new feature with this issue.

We could add a update_thermal_resistance() method to the pipe classes, which would build the thermal resistance matrix, initialize stored coefficients (like it is done in the __init__ methods) and return R_b. This adds the possibility to have time-varying resistances during simulations.

A prototype implementation for the SingleUTube class:

def update_thermal_resistance(self, R_fp)
    # Delta-circuit thermal resistances
    self._Rd = thermal_resistances(
        self.pos, self.r_out, self.b.r_b, self.k_s, self.k_g, R_fp, J=self.J)[1]
    self.R_fp = R_fp

    # Initialize stored_coefficients
    self._initialize_stored_coefficients()

    # Evaluate borehole thermal resistance
    R_b = 1 / np.trace(1 / self._Rd)
    return R_b

[j-c-cook]

I can concur, there is a need for an update_thermal_resistance() method.